Control valves

ABSTRACT

A pressure control valve for providing a fluid pressure which is a substantially fixed value higher than a control pressure comprises a valve member slidable in a cylinder, one end of the cylinder communicating with a source of fluid pressure. The cylinder is provided with a circumferential groove in its periphery and the groove communicates with a drain and is arranged to be uncovered by the valve member as the latter is moved towards the other end of the cylinder by the fluid under pressure. A resilient means is located in the other end of the cylinder, and means is provided for generating a control pressure which is admitted to the other end of the cylinder. The arrangement is such that the valve member will move to control the pressure in the one end of the cylinder to a value proportional to the control pressure plus a substantially fixed value determined by the resilient means.

United States Patent [191 Stefanek [4 1 Oct. 14, 1975 [73] Assignee: C.A.V. Limited, Birmingham,

England 22 Filed: May 13, 1974 [21] Appl. No.1 469,307

[30], Foreign Application Priority Data May 15, 1973 United Kingdom 23004/73 [52] US. Cl. 137/58; 137/84; 137/529; 137/538 [51] Int. Cl. GOSD 13/38 [58] Field of Search 137/58, 82, 84, 85, 529, 137/538 [56] References Cited UNITED STATES PATENTS 2,986,126 5/1961 Werts 137/85 X 3,017,897 1/1962 Seguenot 137/538 X 3,129,563 4/1964 Long 137/85 X 3,739,807 6/1973 Landrus 137/538 X Primary ExaminerRobert G. Nilson Attorney, Agent, or FirmAndrus, Sceales, Starke & Sawall [57] ABSTRACT A pressure control valve for providing a fluid pressure which is a substantially fixed value higher than a control pressure comprises a valve member slidable in a cylinder, one end of the cylinder communicating with a source of fluid pressure. The cylinder is provided with a circumferential groove in its periphery and the groove communicates with a drain and is arranged to be uncovered by the valve member as the latter is moved towards the other end of the cylinder by the fluid under pressure. A resilient means is located in the other end of the cylinder, and means is provided for generating a control pressure which is admitted to the other end of the cylinder. The arrangement is such that the valve member will move to control the pressure in the one end of the cylinder to a value proportional to the control pressure plus a substantially fixed value determined by the resilient means.

3 Claims, 1 Drawing Figure CONTROL VALVES This invention relates to a pressure control valve for providing a fluid pressure which is a substantially fixed value higher than a control pressure.

A pressure control valve in accordance with the invention comprises in combination, a valve member slidable in a cylinder, one end of said cylinder communicating with a source of fluid pressure, a circumferential groove in said cylinder, the groove communicating with a drain and being arranged to be uncovered by the valve member as the valve member is moved towards the other end of the cylinder by the fluid under pressure in said one end of the cylinder, a resilient means located in said other end of the cylinder and means for generating a control pressure which is admitted to said other end of the cylinder, the arrangement being such that the valve member will move to control the pressure in said one end of the cylinder to a value proportional to the control pressure plus a substantially fixed value determined by the resilient means.

One example of a pressure control valve in accordance with the invention will now be described with reference to the accompanying drawing.

Referring to the drawing, there is shown a cylinder in which is mounted a slidable valve member 11. One end of the cylinder 10 communicates with a conduit 12 which incorporates a restriction 13 at its entrance into the cylinder. The conduit 12 communicates with the outlet of a pump 14.

Formed in the wall of the cylinder 10 is a port 16 which can be uncovered to a greater of lesser extent by the valve member 11. Thepressure of fluid within the cylinder acts on the adjacent face of the valve member 11 to produce a force which is opposed by mechanical means. The valve member 11 is moved by the predominating force until a position of equilibrium is attained in which the force acting on the valve member 11 due to the pressure of fluid within the cylinder 10 balances the force generated by the mechanical means. in the event that the output pressure of the pump 14 should rise, then the valve member 11 will seek a new position of equilibrium.

In the example described the mechanical force is generated by a pair of centrifugal weights 17 which move orbitally and therefore apply to the valve member 11 a force which varies in accordance with the square of the speed at which the weights are driven. The pressure of fluid within the cylinder 10 is therefore proportional to the square of the speed at which the weights are driven.

The outlet of the pump 14 also communicates with one end of a cylinder 18 in'which is located a slidable valve member 19. The valve member is loaded by a resilient means in the form of a spring 20, in opposition to the force exerted by the fluid pressure generated by the pump acting on the valve member. The force exerted by the spring 20 is supplemented by the force exerted by fluid under pressure derived from the cylinder 10.

Formed in the wall of the cylinder 18 is a circumferential groove 21 which communicates with a drain, the groove constituting a spill path controlled by the valve member 19. In use, the fluid pressure within the one end of the cylinder 18 and therefore the outlet pressure of the pump 14 is controlled so that in the particular example it is equal to the pressure within the cylinder 10 plus a fixed value determined by the force exerted by the spring.

The use of an annular groove as the spill path from the cylinder 18 means that there is a large variation in the size of the spill path for a very small movement of the valve member 19. The spring force is therefore substantially constant over a wide range of output from the pump 14.

Such a valve as described is of particular use in a fuel pumping apparatus for supplying fuel to an internal combustion engine. In such an apparatus it is often desirable for various control functions to be carried out by pressure responsive members which are subjected to a pressure which varies as the square of the speed at which the apparatus is driven. This pressure can be obtained from the cylinder 10. At the same time it is desirable to provide other control functions which are carried out by members which are subjected to a pressure which is a substantially fixed value above the pressure which varies as the square of the speed. This pressure is obtained from the cylinder 18.

l claim:

1. A pressure control valve for providing a fluid pressure which is a substantially fixed value higher than a control pressure and comprising a valve member slidable in a cylinder, a source of fluid pressure, one end of said clyinder communicating with said source of fluid pressure, a circumferential groove in said cylinder, passage means through which said groove communicates with a drain, said groove being uncovered to said one end of the cylinder as the valve member is moved towards the other end of the cylinder by the fluid pressure in said one end of the cylinder, resilient means located in said other end of the cylinder, means for generating a control pressure which is admitted to said other end of the cylinder whereby the valve member will move to control the pressure in said one end of the cylinder to a value proportional to the control pressure plus a substantially fixed value determined by said resilient means, said means comprising a further cylinder, a further valve member slidable in said further cylinder, one end of said further cylinder being in communication with a further source 'of fluid pressure, the fluid pressure within said further cylinder acting on said further valve member, a spill port in said further cylin der and which is progressively uncovered by said fur ther valve member as it is moved by the fluid pressure within said further cylinder, and mechanical means for generating a force opposing movement of the further valve member by the fluid pressure, the arrangement being such that the pressure within said further cylinder is dependent upon the force generated by said mechanical means, the pressure within said further cylinder constituting the control pressure.

2. A control valve as claimed in claim 1 in which said source of fluid pressure comprises a pump, said further source of fluid pressure comprising a restrictor which is interposed between the outlet of the pump and said further cylinder.

3. A control valve as claimed in claim 1 in which said mechanical means comprises a centrifugal weight. 

1. A pressure control valve for providing a fluid pressure which is a substantially fixed value higher than a control pressure and comprising a valve member slidable in a cylinder, a source of fluid pressure, one end of said clyinder communicating with said source of fluid pressure, a circumferential groove in said cylinder, passage means through which said groove communicates with a drain, said groove being uncovered to said one end of the cylinder as the valve member is moved towards the other end of the cylinder by the fluid pressure in said one end of the cylinder, resilient means located in said other end of the cylinder, means for generating a control pressure which is admitted to said other end of the cylinder whereby the valve member will move to control the pressure in said one end of the cylinder to a value proportional to the control pressure plus a substantially fixed value determined by said resilient means, said means comprising a further cylinder, a further valve member slidable in said further cylinder, one end of said further cylinder being in communication with a further source of fluid pressure, the fluid pressure within said further cylinder acting on said further valve member, a spill port in said further cylinder and which is progressively uncovered by said further valve member as it is moved by the fluid pressure within said further cylinder, and mechanical means for generating a force opposing movement of the further valve member by the fluid pressure, the arrangement being such that the pressure within said further cylinder is dependent upon the force generated by said mechanical means, the pressure within said further cylinder constituting the control pressure.
 2. A control valve as claimed in claim 1 in which said source of fluid pressure comprises a pump, said further source of fluid pressure comprising a restrictor which is interposed between the outlet of the pump and said further cylinder.
 3. A control valve as claimed in claim 1 in which said mechanical means comprises a centrifugal weight. 